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6522: avoid handshaking with register F.

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This commit is contained in:
Thomas Harte
2025-09-28 22:12:53 -04:00
parent 247e92cfa2
commit f9e5b0f0c7
1 changed files with 14 additions and 10 deletions
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Components/6522/Implementation/6522Implementation.hpp
+14 -10
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@@ -23,7 +23,7 @@ template <typename T> void MOS6522<T>::access(const int address) {
}
break;
case 0xf:
// case 0xf:
case 0x1:
// In both handshake and pulse modes, CA2 goes low on any read or write of Port A.
if(handshake_modes_[0] != HandshakeMode::None) {
@@ -57,14 +57,17 @@ template <typename T> void MOS6522<T>::write(int address, const uint8_t value) {
bus_handler_.run_for(time_since_bus_handler_call_.flush<HalfCycles>());
bus_handler_.template set_port_output<Port::A>(value, registers_.data_direction[0]);
if(handshake_modes_[1] != HandshakeMode::None) {
set_control_line_output<Port::A, Line::Two>(LineState::Off);
}
// Avoid handshaking if this was via address 0xf.
if(address == 0x1) {
if(handshake_modes_[1] != HandshakeMode::None) {
set_control_line_output<Port::A, Line::Two>(LineState::Off);
}
registers_.interrupt_flags &= ~(
InterruptFlag::CA1ActiveEdge |
((registers_.peripheral_control&0x02) ? 0 : InterruptFlag::CB2ActiveEdge)
);
registers_.interrupt_flags &= ~(
InterruptFlag::CA1ActiveEdge |
((registers_.peripheral_control&0x02) ? 0 : InterruptFlag::CB2ActiveEdge)
);
}
reevaluate_interrupts();
break;
@@ -196,9 +199,10 @@ template <typename T> uint8_t MOS6522<T>::read(int address) {
registers_.interrupt_flags &= ~(InterruptFlag::CB1ActiveEdge | InterruptFlag::CB2ActiveEdge);
reevaluate_interrupts();
return get_port_input<Port::B>(registers_.data_direction[1], registers_.output[1], registers_.auxiliary_control & 0x80);
case 0xf:
case 0x1: // Read Port A ('IRA').
case 0x1: // Read Port A ('IRA') [with handshaking].
registers_.interrupt_flags &= ~(InterruptFlag::CA1ActiveEdge | InterruptFlag::CA2ActiveEdge);
[[fallthrough]];
case 0xf: // Read Port A ('IRA') [without handshaking].
reevaluate_interrupts();
return get_port_input<Port::A>(registers_.data_direction[0], registers_.output[0], 0);